6.4.2 Headache attributed to primary angiitis of the central nervous system (PACNS)

Previously used term:

Headache attributed to isolated CNS angiitis or granulomatous CNS angiitis.

Description:

Headache caused by and symptomatic of primary angiitis of the central nervous system. Headache is the dominant symptom of this disorder, but lacks specific features.

Diagnostic criteria:
  1. Any new headache fulfilling criterion C
  2. Primary angiitis of the central nervous system (PACNS) has been diagnosed
  3. Evidence of causation demonstrated by either or both of the following:
    1. headache has developed in close temporal relation to other symptoms and/or clinical signs of onset of PACNS, or has led to the diagnosis of PACNS
    2. either or both of the following:
      • a) headache has significantly worsened in parallel with worsening of PACNS
      • b) headache has significantly improved in parallel with improvement in PACNS resulting from steroid and/or immunosuppressive treatment
  4. Not better accounted for by another ICHD-3 diagnosis1.
Note:

In particular, CNS infection, CNS neoplasia and reversible cerebral vasoconstriction syndrome have been excluded by appropriate investigations.

Comments:

Headache is the dominant symptom in CNS angiitis (either primary or secondary). It is present in 50-80% of cases according to the diagnostic methods used, respectively angiography and histology. Nevertheless it has no specific features and is therefore of little diagnostic value until other signs are present, such as focal deficits, seizures, altered cognition or disorders of consciousness. However, the absence of both headache and CSF pleocytosis makes CNS angiitis unlikely.

Primary angiitis of the central nervous system (PACNS) can present with angiographic findings quite similar to those of reversible cerebral vasoconstriction syndrome (RCVS), including multifocal stenosis of the intracranial arteries; recurrent thunderclap headaches should suggest a diagnosis of RCVS and not PACNS.

The pathogenesis of 6.4.2 Headache attributed to primary angiitis of the central nervous system is multifactorial: inflammation, stroke (ischaemic or haemorrhagic), raised intracranial pressure and/or subarachnoid haemorrhage.

The effect of treatment is far less dramatic than in 6.4.1 Headache attributed to giant cell arteritis. Histologically proven primary CNS angiitis remains a serious and not infrequently lethal condition.